Strain dependence of the low-frequency dielectric constants of a few alkali halides

The variation of the low-frequency dielectric constant of NaCl, KCl, and KBr with stress has been determined by subjecting the crystals to uniaxial compressive stresses. Contrary to expectations, the dielectric constant was found to increase on stressing. On n irradiation, the sign of the change in the dielectric constant of the crystals was reversed. This has been attributed to the pinning of the dislocations, whose initial movement under stress might have caused the dielectric constant to increase.